Original subtitles

Hello. Welcome to Gardeners' World,

and a rather special Gardeners' World today

because we're going to devote the whole programme to trees

and celebrate their wonder and magic and mystery.

And I'm here at Nant y Bedd

which is the creation of Sue and Ian Mabberley.

And what they've done is establish this magical garden

set deep in the forest in the Brecon Beacons.

Coming up on today's programme -

Nick shares his top tips

for choosing the right tree for your garden.

No matter if your garden is large or small,

or in the city or in the countryside,

I reckon there is a tree to suit virtually every space.

Arit talks with the environmentalist Al Gore

about the importance of planting more trees for the planet.

Gardeners can play a key role

by helping to enhance awareness of the role the natural world plays

in stabilising and protecting our ecological systems

and the integrity of those systems.

We meet a bonsai enthusiast

who has perfected the ancient art of creating these living sculptures.

This is a lonicera that came from a hedge

and it's something that you can root very, very easily

and look after very easily.

And I meet the world's leading tree authority, Tony Kirkham,

to discuss the role that trees play in our ecosystem.

Our native oak plays host to something like 2,300 species.

It is an incredible tree.

Now, our films from your gardens in today's programme

are an expression of your love of trees,

and the first of these comes from Merseyside.

Hi, my name's Rebecca

and I live just outside of Liverpool with my husband Ross

and I'd love to give you a tour some of the trees

that we've got in our garden today.

Our garden isn't a huge garden,

it's 60 foot by 24 foot,

but we've managed to fit in over 20 trees

so I think it's safe to say that we love, we love our trees.

Quite possibly my favourite tree in the garden

has to be the golden Indian bean trees.

I just love the foliage so much.

They've got these beautiful, big, heart-shaped leaves

that are tissue-paper-thin

and they're the most vibrant shade of lime green.

Our golden Indian bean trees are grafted

which is brilliant for a smaller garden

as it basically means that the stem will stay at that height

and only the head of the tree will grow.

And we're hoping that these trees will grow together

and form an archway.

Another tree that we love are the standard ginkgoes

and we actually have three of these planted

in a pebble trough in the patio,

and we've added some alpines at the base for some extra interest.

The foliage on these is lovely.

It's such a unique shape, it's almost got frills.

And in the autumn, the leaves turn a buttery golden-yellow colour

which just extends that period of interest.

So, hopefully, you've enjoyed having a little look around

all of our trees, and maybe it gave you some ideas

of some trees that you might like to add to your own garden.

I think Rebecca's garden looks absolutely fantastic

and it does show you that you don't need a great big space

to do extraordinary things using trees in your garden.

Now, recently, I went to visit a garden, Hergest Croft Gardens,

in Kington in Herefordshire

to meet the great tree expert Tony Kirkham.

And we walked through the arboretum there on a very rainy day

to discuss the role of trees in our gardens, and indeed in our lives.

Tony, I think everybody would agree that trees are wonderful

but why?

What's wonderful about them?

When we think about the benefits that trees provide us with,

so, without trees, we wouldn't be able to breathe.

They take carbon dioxide, bank it into the tree,

so they make wood from it, store it, and then give us oxygen in return.

So we desperately need that.

Does it have to be trees?

There are lots of plants that will do that as well, aren't there?

There are lots of plants, but the trees are the workhorse.

So, for example, Monty, an oak tree about 100 to 150 years old,

if we took every leaf off that tree

and laid them side by side on the ground,

we would cover an area the size of a football pitch.

And you imagine the work that that's doing, photosynthesising,

taking in carbon dioxide, and giving us the oxygen that we breathe -

I think that really puts it into perspective.

They are incredible machines, really,

and sometimes we take them for granted.

One of the things that has become really topical - and rightly so -

is the role of our gardens for wildlife. Yes.

Now, I know that trees are an integral part of that.

But to what extent? How important are they for wildlife?

It's the habitat, really, that they provide for wildlife.

So, for example, our native oak plays host

to something like 2,300 species alone -

that's fungi, lichens, mosses, insects, mammals, birds.

And of those 2,300, over 300 - 320 to be precise -

are what we call obligate species,

so they will only live on the oak, they can't live on anything else.

Trees bring countless benefits to our world.

But the challenges they're facing are growing year on year.

Generally speaking, today, the biggest threats to trees

are changing climate.

So, the seasons seem to be merging,

and we're going away from four seasons into two.

So autumn merges into winter,

and then spring merges into summer, and plants get mixed up.

Remember, trees have been around for millennia,

and over a very short period of time, you know,

45 years that I've been working with trees,

that has been a very big change.

Trees need a rest.

So, trees are like you and I. We need our sleep.

If we don't get our regular sleep pattern, then we're a bit grumpy,

a bit moody, a bit stressy.

And it's the same with trees -

they need that winter dormancy just to relax and rest

and get everything back to normal, ready for the next growing season.

And that rest period is getting shorter and shorter and shorter.

And then, the growing season where they have to work

is getting longer and longer.

The fact that our world is more interconnected than ever

is causing problems for trees.

Well, the main thing now is

the threat from introduced pests and diseases.

I mean, when I started, probably the same as you, Monty,

Dutch elm disease was the thing.

We were all terrified of Dutch elm. Yeah, yeah.

But it was the only one.

Now the oaks are threatened with acute oak decline,

sudden oak death, and then, in pest terms, oak processionary moths.

And so the list is growing, and there's a whole range of pests

and diseases that aren't necessarily here yet that we don't want.

So what can gardeners do to mitigate those problems?

The first form of defence really is prevention.

Not bringing in any plant material on your travel.

That's... Don't be tempted.

When you go on holiday, you see an olive or something

and you are tempted to bring cuttings back, or seeds,

don't do that.

The problems that trees are facing can seem overwhelming

but we can all play a part in turning this around.

What should we, as gardeners, be doing?

We could all help by planting a tree.

And if you think, if everybody with a garden planted a tree,

20 million people, 20 million trees,

that would be a massive step forward.

In terms of wildlife,

there's a general perception that native trees are better.

I think we should be planting more diversity, different species.

I mean, look at this tree. This is from China.

It lives up to its name.

It's Sorbus splendens.

All these berries will be eaten by birds,

so, even exotic trees are good for bird species.

And when we go to a nursery,

we should be deciding what do we want from our tree?

It's usually ornamental attributes,

so, a good bark, good flower,

good fruit,

a nice-shaped leaf, autumn colour.

And if we can tick all those boxes for a tree,

then that is a really hard-working tree,

and deserves that position in the garden.

So let's all plant a tree.

I'll be chatting to Tony later on in the programme,

talking particularly about the way trees communicate with each other,

it's absolutely fascinating stuff.

But you may feel that, with the best will in the world,

you simply can't accommodate a tree in your garden,

may not even have a garden.

But think again, because there really is a tree

for every situation in every garden.

There are trees that you can grow on balconies,

trees that you can grow in a pot on a windowsill.

And if you want to find out more, then one of the best places to go

is a flower show.

And a few weeks ago, Nick went to Chelsea

in search of tree inspiration.

Ideally, every garden could and should have a tree,

but it's really worth doing your homework.

Getting the right-sized tree, the right-sized space

is so important because you're not just planting for now,

you're planting for the future.

With a huge variety of trees to choose from, it's a good idea

to consider not only your climate and soil conditions,

but also your budget,

and how long you're willing to wait to get that fully matured effect.

With bigger trees, you're buying time.

But don't be afraid to plant a sapling and watch it grow -

young trees often establish better.

30 years ago, I started my first job in horticulture

which was working on a tree nursery,

and I spent that first summer bent double, budding and grafting trees -

a huge proportion of which were malus, or crab apples.

They were hugely popular back then, and they're just as popular today.

And rightly so, because they provide so many seasons of interest

and they're great for wildlife

as the fruit provides food through autumn into winter.

There are lots of varieties to choose from

meaning there's something for every size of garden.

Some will even grow in containers.

As with any tree, always be sure to check the ultimate size,

what soil and light requirements your tree needs,

and you can't go wrong.

Now, this particular cultivar, Winter Gold,

will go up to about four metres

and it starts out in spring

with a mass of white blooms, which are brilliant for pollinators.

It then produces these fruits which are initially green,

and then take on this lovely golden tone in late summer and into autumn.

Now, they persist well into winter so they're brilliant food for birds.

But if you can get in there quickly yourself, then you can harvest them

and make wine or crab apple jelly.

But if you want an even more compact tree,

it's worth thinking about a cultivar called Red Jade.

That's a weeping form

and it only goes up to about two-and-a-half metres.

It's absolutely covered in glossy red fruit

which also lasts well into winter.

Crab apples are easy to grow.

They'll cope with a bit of shade

but the fruit will ripen even better in a sunny position.

So it's well worth having a look around

and seeing which malus is going to suit your garden.

In my book, the best small garden trees

are those that provide you with interest throughout the year.

One of my absolute favourite small garden trees is this -

it's Rhus typhina.

And this specifically is a cultivar called Dissecta.

It's called that because you've got

these really sort of chopped-up fine leaves.

In the ordinary form, they're solid leaves.

And it's incredibly adaptable,

so it'll grow virtually anywhere in the UK.

Now it's great small garden tree because it'll only go to about two

and a half metres tall, but it's got interest throughout the year.

So you can see the old flower heads here from last winter

and then the flower heads that have been produced this year,

and they'll persist all the way through winter, even when the leaves

have dropped off.

Now the leaves are pretty much the star of the show.

In fact, I defy you to come up with a tree

that has better autumn colour than this.

It's got a fantastic range of really vibrant red, orange

and yellow leaves that persist for about three weeks.

It does come with one small challenge,

and that's down at the root level.

Its roots are fairly determined to run and send up new suckers,

so they'll travel out from the centre and then suddenly

send up a new tree.

A simple way to manage it is to just put in a barrier underground,

which will prevent those roots of spreading.

There are plenty of trees that will grow happily in a container

given the right care, and growing a tree in a pot means

you can have one almost anywhere in the garden,

even on a patio or balcony.

If you are looking for a compact, evergreen statement piece

for a small garden or courtyard,

then I reckon that this is the tree to go for.

It's Pinus mugo pumillio.

Now, unlike most of the pines,

which are absolutely vast, this one is naturally a baby.

In fact, it's known as the Dwarf Mountain Pine, and this particular

specimen is 50 years old.

But it's something that you can start yourself at home with a

medium-sized specimen and gradually train it over the years.

I think it adds that fantastic sort of oriental look to small spaces.

Like most pines, Pinus mugo isn't particularly fussy about its soil

type, as long as it isn't heavy clay.

It will benefit from regular watering in the hottest of summers

as its roots lie very close to the surface of the soil.

It has to be said, there's a pretty fine line between what constitutes

a large shrub and a small tree.

This is a prime example.

It's a brilliant plant.

It's called Heptacodium miconioides.

It's often known as Seventh Son of the Seventh Son,

and that's because of the way its flowers are structured.

So you've essentially got a cluster of six flowers,

with one in the centre.

Now it really is the large shrub or the tree with it all.

Right now we're in late summer going into autumn, and it's covered

in massive blooms, which are absolutely loved by pollinators.

But once the flowers have dropped those Calluses, those little pink

supports on the back of the flowers sustain until November or December.

So all this looks like a pink flowered shrub, then through the

winter you've got these fabulous sort of ghostly stems.

You can see the bark is peeling off in beautiful strands.

Now it's genuinely small, so it'll never get

to more than about four metres or so high.

And, of course, because it's got that open quality, it's good

as a host for other plants, things like bitter clematis, which flower

in the end of autumn would be absolutely perfect

to grow up through this.

So for an all season large shrub or small tree,

I reckon Heptacodium miconioides is the one to try.

One way to maximise your vertical space and ensure you get the most

from a fruit tree is to grow them against a wall or a fence.

Espalier apples and pears are ideal for this.

Now, this particular specimen is a conference pear

and this is probably about 50 years old.

You can see it's seriously gnarly, but if you want to grow them

yourselves, you can buy them pre-trained as a relatively young

tree, two or three years old. Once they're in the ground,

they will fruit in one to two years' time,

Or you can just take a tree yourself

and gradually train it over the years.

Both pears and apples can be grown in this way, and you can see there's

a basic T framework here from which all of these spurs emerge.

And it's these spurs that produce the fruit,

and so they need to be pruned during the winter

down to about two buds.

And what you'll find is in spring, they come into bloom,

masses of white flowers, brilliant for the pollinators.

Then you'll get embryonic fruit through summer and then harvestable

fruit in the autumn.

You can grow Espaliers in a number of different ways.

The classic thing is to grow them against a wall, trained out flat,

but you can equally put them onto a garden fence or an interesting

way to use them is mid-garden, so virtually use them

as a screen or a fence.

So if you're looking for a compact tree that delivers lots of interest

and is productive, then it's really worth

considering growing Espaliers.

No matter if your garden is large or small,

or in the city or in the countryside,

I reckon there is a tree to suit virtually every space.

I agree with everything Nick says,

but there aren't many gardens that could accommodate

these Douglas firs.

It's not so much the footprint.

It's how they soar up into the air.

This is about 85 years old, and yet already it's 150 feet tall.

And there is no other living thing on the planet that can match it.

Still to come on today's programme...

Arit chats with the former American Vice President and environmentalist

Al Gore, about what we can all do to protect our trees

and his mission to get us planting more.

Worldwide, there's now a global effort to plant one trillion trees,

but we have to plant the right kind.

We climb high into the canopy of a Staffordshire woodland

to explore the very latest in cutting edge carbon science.

We are taking the laboratory out into the forest and asking ourselves

how that forest will respond to the changed atmosphere

that will be all around everybody by the middle of the century.

And we get a masterclass in how best to plant a tree,

when Toby visits a North London school.

I actually have to name it, I name everything.

Ted? No, it's not a Ted. Aw.

But first, we're going to Ellsbury to meet a bonsai artist.

The ideal tree will look like a mature tree

with ideal proportions.

Something that you can stand underneath, sit around the base

of the trunk and look up into the leaves.

My name is Harry Harrington, and I'm a bonsai artist.

When I worked as a gardener in my twenties, I would see

these trees that the owner of the garden had.

And they were just saplings in pots, but I would see them every day

and having this, this tree in my hand for me

was just an amazing feeling.

And that is the very essence of bonsai for me

is you have this beautiful living entity that you can capture

and nurture and look after.

There was a big mystique about bonsai, and it was seen

as something very unattainable.

But I think in the past 30 or 40 years, particularly in Europe,

we've realised that you can use very, very common European trees.

In bonsai, we have naturalistic styles and we have abstract styles

and naturalistic trees is the tree that you would still see growing

in a field or on the horizon.

Abstract styles would be more caricatures of trees.

They may have cloud pruning, or they may be something

that is a thing of beauty, but doesn't look like a tree

that you would ever actually see in nature.

If you try and bring a tree inside for a day or two, that's absolutely

fine, and it's something that's very traditional for the Japanese

to show their one tree for a few days.

But if you try and keep a tree inside on a long term basis,

it will just gradually diminish in vigour and health.

When we have a branch that's not pointing in the right direction,

what I'll do is I will coil copper wire around that branch

and this enables me to place it exactly where I want to,

within the design of the entire tree.

I can put bends into the shoots and I can completely redirect them.

The wire then holds that branch in its new position until it's set,

which can be anything from a few weeks to six months later.

Then the wire is cut away.

So when we're designing the tree, we're designing the branches.

But we also design the roots and the surface roots,

and they're very important, something we call the nabari.

And we have various techniques, including growing a tree on top

of ceramic tile to ensure that it grows lateral roots

and no plunging roots.

And after four or five years of growing in the grounds,

you can actually have quite an impressive nabari build up.

So this is a great piece of material for a bonsai.

This is boxwood, it's 20, 30 years old.

It's been dug out of the grounds and it's survived.

It's got a new root system growing.

And the important thing is, we've got a nice fat trunk

on which to start developing branches and start putting a design

into this plant.

However ugly it is now, you could turn it into a beautiful

bonsai in 10, 15 years.

So this is a Lonicera that came from a hedge

and was just a basic block of wood.

And it's something that you can root very, very easily and look

after very easily, and they create style.

To your right is a privet.

And this again came from a hedge row as a big lump of wood.

Rooted really easily,

and over 15 years I've developed and developed it.

And, again, very easy to look after species.

One of the lovely things about having a bonsai collection

is you will start to associate some of your bonsai with different events

in your life, whether they're good or bad.

You'll remember the times where things have been a bit

of a struggle and you're gone out into the garden, worked on the tree

and just being able to relax and get away from life.

I have one tree that I obtained the trunk literally the day

before my daughter Alice was born, and this was 11 years ago.

So Alice's tree has taken a journey alongside my daughter

growing up, and that gives it some additional poignancy.

There is also trees that I have photographed my children

alongside in various stages of both their development.

And it's lovely to look back and see how everything sort of grows

together as you nurture them.

So I think when you accomplish a design in a tree,

particularly after 10 or 15 years,

there is a buzz, it's something that you've created yourself.

And it can only improve as time goes on.

And it will outlive me, and my children and my grandchildren.

Whenever I see bonsai, created with the same sort of skill

and experience that Harry has shown in his, I always marvel at the fact

that these are old, mature trees, sometimes as old as a big oak tree,

but just condensed and distilled down into miniature.

They really are completely fascinating.

Earlier in the programme, I was chatting to Tony Kirkham,

the great tree expert at Hergest Croft Gardens,

and our talk turned to the way that, recently, more and more discoveries

are being made about the ways that trees communicate

with each other.

We've been discovering more and more about what you might call

the secret life of trees. Mm.

Well, you're absolutely right.

We are learning more about how trees communicate to each other.

They do talk to each other, but in a different way

to...to what we do.

First of all, underground, there's an incredible network

going on between tree and fungi.

There's mycorrhizal fungi that's connecting all the roots together.

We call it the "wood wide web".

They work together in a symbiotic relationship, sharing resources.

So the trees are the host, the fungi helps the tree

and all the resources are switching

from one tree to another and from the fungi to...to the trees.

So if a tree feels a bit under the weather,

then the other trees will help it and bring it back.

I can give you an example.

I went into a redwood forest and saw an albino redwood, pure white.

Now that tree can't survive without chlorophyll.

It had zero chlorophyll.

The only way it could have been growing happily and healthily

is by other trees supporting it.

As well as helping and nourishing each other,

trees also seem to have developed early warning systems for dealing

with the threat of certain pests.

I've seen oak trees where they've been under attack from winter moth,

but when those groups of caterpillars get too big

or too large for a branch or for a leaf,

they can reduce respiration,

increase the tannin levels in the leaf,

so the leaves become very bitter to the caterpillars.

Then the tree can communicate to other trees and say,

"You need to shut down and make your leaves unpalatable

"for these caterpillars."

How they do that is probably emitting pheromones

through the leaves, so through smells and taking smells

in through respiration, electrical impulses and also

through the root system.

You would think that in survival of the fittest,

individual trees would be trying to outcompete their neighbours,

not...not to work with them. Yeah, you would.

But remember in a woodland, Monty,

it's about building a community that gives them the protection

from winds, from weather, animals, etc.

So it's about building that family and that community

that can survive better in numbers, rather than on their own.

The information that we are discovering about this

"wood wide web" is endlessly fascinating and surprising.

What do you think that we don't yet know about trees?

Where is the research taking us?

Well, it's certainly taken us into the...to give us a better

understanding of trees, and I think there's a long way to go yet.

So, for example, I know there's research being done

on how trees like pines,

when they're under attack from aphids,

they can send out a scent, a pheromone that ladybirds pick up.

And that scent is like blood in the sea to a shark.

It attracts the ladybirds that come in and then eat the...eat the aphids

and manage the aphids for the pine.

So they're not just communicating with each other,

they're communicating to insects and other creatures.

That's right. Yeah. Extraordinary.

There is so much to learn, really, isn't there,

about how trees work and this communication?

I was left with so much to think about from my day with Tony,

but...but certainly this idea of trees communicating on the ground

and through their leaves is mind boggling.

And sitting here, you realise that all these thousands of trees

in the landscape are all interacting together,

speaking a language which we can only hear the faintest whispers of.

Now, Arit had the opportunity to talk

to the former US Vice President, and lifelong environmentalist, Al Gore,

about the significance and environmental role of trees.

You're never really very far away from a tree in the UK.

Whether you're lucky enough to have them in your garden

or surrounded by them in the park or countryside,

or pass them when out and about,

trees in all their wonderful, beautiful forms are everywhere.

And it's easy to take them for granted.

They are constants and markers in our lives and can often

be older than us.

In recent decades, we've begun to understand the importance of trees

and the role they play in our changing climate.

For former US Vice President Al Gore - Nobel Peace Prize winner

for informing the world of the dangers posed by climate change -

getting this message out has been his lifetime's work.

Al, it's so great to see you, and thank you for taking the time

to chat with me today.

It's a great honour to be asked to be on with you.

Clearly, your passion for this planet is...is clearly

in your blood and I know that you grew up on a farm.

And I wonder if that's really where the relationship started

with you in the land?

And what was your connection to trees?

My childhood had two parts to it every single year.

There was the concrete of the city in Washington DC

and then there was the farm with trees

and pasture and animals and blue sky.

And it was pretty easy to make a choice between those two venues.

And I really enjoyed the time I was able to spend

being closer to nature.

I didn't really think of it in those terms as a child,

but my earliest lessons on environmental protection

were from my dad following him across the farm,

three, four, five, six years old.

And then it was just a hop, skip and a jump on to climate

when I had a professor in college who focused my interest on that.

And I can feel it now when I get back and walk

through the forest and we have trails here now

through the trees, and it's just, it's renewing.

Oh, that's fabulous to hear.

And I have planted 10,000 new trees here on the farm.

It's a small amount compared to what we need worldwide.

There's now a global effort to plant one trillion trees.

But we have to plant the right kind and we have to avoid

these monoculture forests that are just good

for cutting them down, making paper or cardboard or something.

You don't get the rich web of biodiversity that you find

in old-growth forests or mature forests that have multiple species.

In the UK, over half of our nation are keen gardeners,

and in the last 18 months,

we've had another three million gardeners join the band

and this is very much about how we want to know, as gardeners,

what can we be doing?

You can join and support the organisations

near you that are fighting to protect natural land and encourage

community leaders to protect these valued resources.

Whether you're planting a single tree in your garden or working

to restore biodiversity across a larger landscape.

That's really good to hear.

And I love the fact that, you know,

you're saying just even that one tree

makes you part of a bigger community, which is so important.

What's your take on the fact of how we are saving

our existing global forests?

It's important to highlight the incredible efforts of indigenous

communities who serve as land defenders and so much of the world

and protect forests around the globe.

Then we should do more to learn from them about how we can

effectively protect our planet's ecology.

And gardeners can play a key role by helping to enhance awareness

of the role the natural world plays and stabilising

and protecting our ecological systems

and the integrity of those systems.

I know that you're incredibly busy, but do you get time to kind of

go out and still have woodland walks

and how does that make you feel when you...when you get to do that?

I make time for it, and I just find it, as I've said before,

calming and renewing.

We know from the science and from our own feelings

that, when we tune into them, that being in the forest

and being in nature is good for us.

I am so, so thrilled to have spoken to you and listened to your insights

and your...your personal thoughts.

So thank you so much, Al.

Thank you, Arit.

I realise that I normally see trees from the ground up

and peering up at them,

so it's lovely to have the opportunity to get up here

into the treehouse and be in the branches,

surrounded by all these leaves.

Nothing else makes you realise just how many leaves

there are on a large tree.

And every one of these leaves is playing a role in capturing carbon

and releasing oxygen.

And Frances has been discovering more about this

via an extraordinary new project.

Hidden in the heart of the Staffordshire countryside,

something very special is happening.

And when you look up into the canopy,

you realise this is anything but a walk in the woods.

This woodland is a site of the Birmingham Institute of Forest Research,

known as BIFoR, a £50 million international project

to detect changes in a mature woodland,

brought about by the increasing carbon dioxide in our atmosphere.

Head of the 40-strong team of scientists working on this ongoing

ten year project is Rob MacKenzie.

Rather than putting plants into a laboratory,

we are taking the laboratory out into the forest

and asking ourselves how that forest

will respond to the changed atmosphere that will be all

around everybody by the middle of this century.

We used to think about forests like this as just gently turning

over in a state of balance.

But, of course, then we realised that we're changing the goalposts.

As far as the forest is concerned,

we have been pushing it and pushing it through changes in carbon dioxide,

changes and pollution due to traffic, power stations and fertiliser use.

All of those things have been like a continual set of knocks

to the system.

And so it's a bit much to expect the system to just continue

to absorb those knocks. That's what we're worried about.

Each year, across the world, temperate forests, not too hot,

not too cold, soak up about as much carbon dioxide as is released

by the EU and UK combined,

carbon dioxide which would otherwise stay in the atmosphere

and contribute to global warming.

The question is, can they keep doing it if we keep pushing them

with more and more carbon dioxide in the atmosphere?

To answer that, Rob and his team have created an atmosphere

in this semi-natural deciduous woodland, which experts calculate

reflects that of the year 2050.

It involves taking pure carbon dioxide, mixing it with air,

piping it up the towers

and releasing it, very carefully, under computer control,

into the patches that we want to experience

that future atmosphere.

These trees are being exposed to just over a third more carbon dioxide

than they'd be receiving today,

and the first part of the experiment is trying to understand

what's going on in the canopy when this happens.

Up here, this is the domain of the oaks,

and they're dominating the process of photosynthesis,

which is the start of the whole chain of reaction

that we're interested in studying.

Photosynthesis is the process

by which CO2 and water,

by the power of sunlight, are converted into sugar, into food,

and that food powers the growth of the plants, but also the growth

of every other single living thing around us in this forest.

Sugar is created through photosynthesis,

and is the initial store for carbon from the atmosphere.

The question is, what happens to the extra sugar created

through the raised levels of carbon dioxide?

We need to measure almost everything you can think of.

And so all around this patch, there are measurements going on.

We're making measurements of the amount of leaf

up in the canopy,

how much of it falls down onto the ground.

We're making measurements of the sap flowing up through the stem

of the tree. That's what this is, here.

Of course, one of the classic places that a tree can store carbon

is in its trunk, building wood.

So one of the measurements that we make is the girth of the tree.

We measure it continuously using this band.

We then look at all the trees in each patch, total up how much

they're growing, and what we find is more growth in the patches

that are getting the extra carbon dioxide.

So some of the carbon dioxide, some of the sugar has been put

into growing the girth of the trees.

So, above ground, the raised carbon dioxide is having the effect

of boosting the size of the tree trunks.

But what is this sugar hit doing to the rest of the forest?

A lot of what we're finding is happening below ground.

That's difficult to see.

One of the ways that we do it is by putting cameras

into the soil repeatedly and measuring the same root

as it slowly grows over the course of a season.

And we're finding that there is more root.

Those roots are exchanging chemicals with the fungus

that's around the roots, trading sugar in order to get

the rest of what they want for a balanced diet.

So far, what we're seeing is a positive effect

from increasing carbon dioxide.

We're finding that there's more of everything

below ground, more life.

While for now, this mature forest and the plants and fungi in it seem

to be thriving, with carbon dioxide levels set to rise even further

after 2050, Rob's team don't yet know if this ecosystem can continue

to respond favourably to the changed balance of nutrients.

What we find is that the forest is responding resiliently.

I feel I know the forest well enough to say it's even responding

valiantly to the push that we're giving it,

because we are giving it a very big push.

But however valiant the response of the forest is,

it can never be enough to do the hard work

that we should be doing in reducing fossil fuel emissions.

If we just expect forests to do all the work for us,

we're just going to be disappointed.

One thing is for sure, our mature trees are doing an incredible job

in soaking up unwanted carbon dioxide.

These guardians of our environment would take hundreds of years

to replace, and we should do everything we can to protect them,

whether it be in our forests, parks or gardens.

Doing so could be the key

to ensuring the future of our planet.

The way that Professor Rob MacKenzie and his team have set up

that outdoor laboratory and are using trees to get as much

knowledge and information to help us all face the problems that lie

ahead of us, whether we like it or not,

is inspiring and encouraging.

Now, for our last visit to one of your guns,

we've been sent this film from Paul Morrison near Morpeth.

Hi, Gardeners' World.

I'm Paul and I live in Northumberland, I just want

to show you around my garden.

This is a photo that I did a couple of years ago, and many plants

with evergreens and little dwarf conifers.

I've planted it quite closely because I want instant effects,

straight away.

This is part of my back garden.

This has been planted up a number of years now.

Absolutely just love trees.

But it's trying to find

the right tree for the right location.

This is called Acer griseum.

Had this one in about 30 year.

It just has an amazing peeling...

..peeling bark.

Quite slow-growing.

And again, amazing autumn colour.

And half up the border, they're absolutely crammed

with Japanese maples and acers and...

..is coming through everything.

This is called the wedding cake cornus,

and it grows up in tiers, like a wedding cake,

and it gets lovely white flowers on in the summer

and it gets the most amazing autumn colour -

it goes like a bright yellow in the autumn.

A really nice tree for a small garden.

This tree here is Betula utilis jacquemontii.

It's really, really lovely for winter interest.

It's got an amazing bark, and the pure brilliant white

looks great in a mixed planting, or a mixed border.

It doesn't get too big,

so it'll grow in a normal-sized garden.

And I would said this one is definitely a most.

Hope you've enjoyed the tour of my garden in Northumberland,

Gardeners' World. Thank you for watching.

Take care, bye.

Yes, Paul, I did enjoy your garden,

and thank you very much for sharing it with us.

It's fine to talk about the importance of planting trees,

but there is a right way to do it,

and certainly it helps

if you plant them so that they thrive from day one.

And Toby has been to a school in North London,

where they've been doing some tree planting, to talk to them

about the trees that they've chosen

and give them some advice on how best to go about it.

Most schools lucky enough to have an outdoor space

or playing fields, use them for social gathering and sports,

and that's great.

However, here at the Torridge Academy in London,

they use some of their site for something completely different.

In partnership with the local charity Grow,

who work with schools and volunteers,

they're taking their students from the classroom to the farm

on five acres of land that's given over

to growing fruit and veg.

Today, we're going to harvest some cabbages, which are going to go

into the school canteen and into our weekly box scheme,

so I'm going to show you how to do it, first of all.

Farm manager Sarah Allen-Jones works with this and other schools to bring

teaching to the outdoors.

Really nice.

We'll have food tech lessons on the farm where they'll come

and harvest veg and learn about seasonality,

and then the next week they'll cook it.

We have science lessons out here.

We've had lessons on decay where we look at the compost heap

and turning the compost heap to see the different levels.

And we also have creative writing out here as well.

And the idea is that, over the years,

we'll have every subject coming out to the farm,

and that it can be a real learning hub for the school.

Sowing the seeds of ideas, sowing cabbages,

but also you've got plans for planting trees. Yes.

Yeah, and that's something that we...

It was really important to do with young people,

to show that they can have an impact on the world.

They can plant something now

and they can come back in ten years' time and it'll still be there.

As they use their produce for school meals,

it makes sense for them to plant fruit trees to add to the menu.

Oh, and we've got some good ones here.

This one is a pear called Conference Moors.

It's like a regular Conference pear -

super reliable, self-fertile, looks after itself,

but you get a bit more - the fruit are bigger.

And what I love about pear trees in the school garden situation

is they flower so early in spring - they're there

for the early pollinator,

so great for lessons around what pollination

and insectivorous life.

And then, over here, what's this? A miracot.

Now, a miracot is an unlikely marriage between a mirabelle plum,

or a hedgerow plum, and an apricot.

It's as tough as the hedgerow plants that you see flowering in early

spring, but also has the lovely flavour of an apricot.

I mean, the fruits are like plums.

What they get from the apricot is this freestone ability,

which means that when you open them up, the stone inside doesn't stick

to the flesh, which is always nice.

And there's a hazel. I'd always recommend having a hazel tree

in a school garden.

This is Tonda Gentile Trilobata.

Now, what makes this so good is it's an Italian variety,

and it's the one they use for making those lovely chocolate spreads.

But like all hazels, it does need a partner to be pollinated.

So a regular hedgerow type with this is just perfect.

But even if you don't get nuts,

or squirrels steal them all before you get them,

hazel is so brilliant.

It's such a useful plant because all the side shoots

and suckers that come off this,

they make such useful building materials for making wigwams,

arches and, of course, pea sticks to hold up the cut flowers.

The students are raring to go.

So I'm going to give them a lesson in tree planting.

What I want you to tell me is how deep you think that needs

to be planted. How deep do we need the hole?

I think, like, where it is there.

So we've got the top of the compost there.

Mark it on the spade.

That is how deep your hole needs to be.

Yeah, I'll just make this hole a bit squarer, a bit larger,

cos if it's square, the roots can get to the corners

and find their way out. That makes sense.

What do you know about them, regarding the bees and pollination?

The bee flies in and then, like, takes the pollen and, like,

rubs it around its back and stuff.

Then the bee goes, and then...

But it like falls off its body

so that it pollinates flowers on lots of different occasions.

So it's very clever.

Think about this, right? Back when the time of the dinosaurs,

there were no bees.

There's only conifers, trees without flowers.

Isn't that mind-blowing? It is.

We've also got apple variety Hidden Rose,

with a delightful pink flesh.

So why do you think trees are good?

I think trees are good

because, like, they're just so calming.

And if you just take your time to just look at them,

then you can just see the beauty and, like, all the life that's

living in them. It's like...it's kind of like a big house

for like bugs and like birds.

It's beautiful.

It absorbs all the carbon dioxide

and also it lets out,

like, really clean, fresh air.

So if you're ever by a tree, you just have to like, smell

all the lovely fresh air. Sniff it all up. And give tree hugs.

Tree hugs are awesome.

Yeah, the trees give the best hugs ever. Brilliant.

Now, there is another ingredient to go on this.

Now, do you know what this is?

It's fungi.

Yeah, it's just got to be in contact with the roots, and that way

the fungi will go into the roots and connect with the other fungi

in the field and the rest of the food.

So that way it gets its nutrients.

It is, yeah, it's sort of a really complex process.

But the tree, in exchange for all the fungi, bringing it food,

nutrients and water, gives sugar.

So it's kind of...kind of a trade. Like a trade. Exactly.

It's important to stake young trees while they establish.

The wind in the whole country largely comes from the southwest.

So you always put a stake on the southwest side of a tree.

OK. Right?

And that way, when you lash the tree to the stake to protect it

from the wind, the tree falls away from the woodwork

and doesn't rub against it and get damaged.

The tree will flourish if you backfill with soil

and firm it in.

I actually have to name it, I name everything. Do you? Ted.

No, it's not a Ted.

Do you see Ted in this?

I'm very disappointed in you. Adam.

Yeah, we can name it Adam. Yeah. Yeah, Adam!

We've gone Adam.

Adam's apple. Very good.

Well, I sat the trees in. Done a good job on that.

Excellent.

Thank you. Thank you.

Most vital of all,

make sure your tree gets plenty of water in the first year

while its roots establish.

It's often said that when you plant a tree,

you do it for your grandchildren, but today,

well, I've learned the profound importance of getting

young people involved.

I'll tell you what, with such inspirational, wonderful young

people coming through,

there's hope for this planet yet.

Of course, it's extra important that we get children to plant trees

and learn about them and be interested in them

because it is their world that trees are going to play

such an important role in.

And if you want to plant trees,

you might like to take part in the Plant Britain project

that Countryfile has established, where they're aiming to plant

three quarters of a million trees over the coming two years,

and you can get all the details about it from our website.

That's it for today.

And I do hope this has inspired you to go out and just make the most

of the wonderful trees we have, wherever you are.

And if you've got a garden, to plant a tree.

They are wonderful for wildlife.

And from day one, however small that tree is, I can promise you

they're completely fascinating.

I am back at Longmeadow next Friday at eight o'clock.

So join me, Patti and Nelly then.

Bye-bye.